Introduction

Let's visit Hawaii and review what has happened to the native flora since humans arrived.

• Native flora consisted of 1200-1300 species prior to Polynesian contact, about 90% of which were found nowhere else on earth.

• At the time of European contact - Captain Cook's voyage, 1778 - the flora contained about 30 species introduced by the Polynesians, examples include:¹
  • breadfruit - Artocarpus altilis

  • coconut - Cocos nucifera

  • taro - Colocasia esculenta

  • yam - Dioscorea (3 species)

  • sweet potato - Ipomoea batatas

  • banana - Musa acuminata hybrids

  • sugar cane - Saccharum officinarum

  Polynesian immigrants also brought a variety of animals.

  • dog

  • a jungle fowl

  • pig

  • rat

• Today the native flora consists of roughly 1000-1100 species, i.e., 100-200 native plant species are already extinct. About 30% of those that remain are considered threatened or endangered.

• One century after Captain Cook's first contact about 150 introduced species were known from the islands. Today over 800 introduced species are known. Almost one-half of the species of vascular plants found on the Hawaiian Islands are introduced. Moreover, most of the plants that you see when you visit the Hawaiian Islands are not native, especially in the lowlands.
  • Kahili ginger - Hedychium gardnerianum

  • Guava - Psidium guava

  • Passion flower - Passiflora mollissima

  • Lantana camara

  • Tibouchina urvilleana

Invasive exotics now pose at least as great a threat to many Hawaiian plants as direct habitat destruction. Goats and pigs disturb the native vegetation, and many invasive exotics capitalize on the disturbances they cause. They also invade undisturbed habitat, some - notably the Kahili ginger and Tibouchina urvilleana - forming dense, monospecific stands that exclude native plants.